thermal: zx2967: add thermal driver for ZTE's zx2967 family

This patch adds thermal driver for ZTE's zx2967 family.

Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

3 files changed, 267 insertions, 0 deletions

diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index 3912d24a07b1..776b34396144 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -445,4 +445,12 @@ depends on (ARCH_QCOM && OF) || COMPILE_TEST
 source "drivers/thermal/qcom/Kconfig"
 endmenu
 
+config ZX2967_THERMAL
+        tristate "Thermal sensors on zx2967 SoC"
+        depends on ARCH_ZX || COMPILE_TEST
+        help
+          Enable the zx2967 thermal sensors driver, which supports
+          the primitive temperature sensor embedded in zx2967 SoCs.
+          This sensor generates the real time die temperature.
+
 endif
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index adcf3cc90859..7adae2029355 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -57,3 +57,4 @@ obj-$(CONFIG_TEGRA_SOCTHERM)	+= tegra/
 obj-$(CONFIG_HISI_THERMAL)     += hisi_thermal.o
 obj-$(CONFIG_MTK_THERMAL)       += mtk_thermal.o
 obj-$(CONFIG_GENERIC_ADC_THERMAL)       += thermal-generic-adc.o
+obj-$(CONFIG_ZX2967_THERMAL)    += zx2967_thermal.o
diff --git a/drivers/thermal/zx2967_thermal.c b/drivers/thermal/zx2967_thermal.c
new file mode 100644
index 000000000000..a5670ad2cfc8
--- /dev/null
+++ b/drivers/thermal/zx2967_thermal.c
@@ -0,0 +1,258 @@
+/*
+ * ZTE's zx2967 family thermal sensor driver
+ *
+ * Copyright (C) 2017 ZTE Ltd.
+ *
+ * Author: Baoyou Xie <baoyou.xie@linaro.org>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/thermal.h>
+
+/* Power Mode: 0->low 1->high */
+#define ZX2967_THERMAL_POWER_MODE       0
+#define ZX2967_POWER_MODE_LOW           0
+#define ZX2967_POWER_MODE_HIGH          1
+
+/* DCF Control Register */
+#define ZX2967_THERMAL_DCF              0x4
+#define ZX2967_DCF_EN                   BIT(1)
+#define ZX2967_DCF_FREEZE               BIT(0)
+
+/* Selection Register */
+#define ZX2967_THERMAL_SEL              0x8
+
+/* Control Register */
+#define ZX2967_THERMAL_CTRL             0x10
+
+#define ZX2967_THERMAL_READY            BIT(12)
+#define ZX2967_THERMAL_TEMP_MASK        GENMASK(11, 0)
+#define ZX2967_THERMAL_ID_MASK          0x18
+#define ZX2967_THERMAL_ID               0x10
+
+#define ZX2967_GET_TEMP_TIMEOUT_US      (100 * 1024)
+
+/**
+ * struct zx2967_thermal_priv - zx2967 thermal sensor private structure
+ * @tzd: struct thermal_zone_device where the sensor is registered
+ * @lock: prevents read sensor in parallel
+ * @clk_topcrm: topcrm clk structure
+ * @clk_apb: apb clk structure
+ * @regs: pointer to base address of the thermal sensor
+ */
+
+struct zx2967_thermal_priv {
+        struct thermal_zone_device      *tzd;
+        struct mutex                    lock;
+        struct clk                      *clk_topcrm;
+        struct clk                      *clk_apb;
+        void __iomem                    *regs;
+        struct device                   *dev;
+};
+
+static int zx2967_thermal_get_temp(void *data, int *temp)
+{
+        void __iomem *regs;
+        struct zx2967_thermal_priv *priv = data;
+        u32 val;
+        int ret;
+
+        if (!priv->tzd)
+                return -EAGAIN;
+
+        regs = priv->regs;
+        mutex_lock(&priv->lock);
+        writel_relaxed(ZX2967_POWER_MODE_LOW,
+                       regs + ZX2967_THERMAL_POWER_MODE);
+        writel_relaxed(ZX2967_DCF_EN, regs + ZX2967_THERMAL_DCF);
+
+        val = readl_relaxed(regs + ZX2967_THERMAL_SEL);
+        val &= ~ZX2967_THERMAL_ID_MASK;
+        val |= ZX2967_THERMAL_ID;
+        writel_relaxed(val, regs + ZX2967_THERMAL_SEL);
+
+        /*
+         * Must wait for a while, surely it's a bit odd.
+         * otherwise temperature value we got has a few deviation, even if
+         * the THERMAL_READY bit is set.
+         */
+        usleep_range(100, 300);
+        ret = readx_poll_timeout(readl, regs + ZX2967_THERMAL_CTRL,
+                                 val, val & ZX2967_THERMAL_READY, 300,
+                                 ZX2967_GET_TEMP_TIMEOUT_US);
+        if (ret) {
+                dev_err(priv->dev, "Thermal sensor data timeout\n");
+                goto unlock;
+        }
+
+        writel_relaxed(ZX2967_DCF_FREEZE | ZX2967_DCF_EN,
+                       regs + ZX2967_THERMAL_DCF);
+        val = readl_relaxed(regs + ZX2967_THERMAL_CTRL)
+                         & ZX2967_THERMAL_TEMP_MASK;
+        writel_relaxed(ZX2967_POWER_MODE_HIGH,
+                       regs + ZX2967_THERMAL_POWER_MODE);
+
+        /*
+         * Calculate temperature
+         * In dts, slope is multiplied by 1000.
+         */
+        *temp = DIV_ROUND_CLOSEST(((s32)val + priv->tzd->tzp->offset) * 1000,
+                                  priv->tzd->tzp->slope);
+
+unlock:
+        mutex_unlock(&priv->lock);
+        return ret;
+}
+
+static struct thermal_zone_of_device_ops zx2967_of_thermal_ops = {
+        .get_temp = zx2967_thermal_get_temp,
+};
+
+static int zx2967_thermal_probe(struct platform_device *pdev)
+{
+        struct zx2967_thermal_priv *priv;
+        struct resource *res;
+        int ret;
+
+        priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+        if (!priv)
+                return -ENOMEM;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        priv->regs = devm_ioremap_resource(&pdev->dev, res);
+        if (IS_ERR(priv->regs))
+                return PTR_ERR(priv->regs);
+
+        priv->clk_topcrm = devm_clk_get(&pdev->dev, "topcrm");
+        if (IS_ERR(priv->clk_topcrm)) {
+                ret = PTR_ERR(priv->clk_topcrm);
+                dev_err(&pdev->dev, "failed to get topcrm clock: %d\n", ret);
+                return ret;
+        }
+
+        ret = clk_prepare_enable(priv->clk_topcrm);
+        if (ret) {
+                dev_err(&pdev->dev, "failed to enable topcrm clock: %d\n",
+                        ret);
+                return ret;
+        }
+
+        priv->clk_apb = devm_clk_get(&pdev->dev, "apb");
+        if (IS_ERR(priv->clk_apb)) {
+                ret = PTR_ERR(priv->clk_apb);
+                dev_err(&pdev->dev, "failed to get apb clock: %d\n", ret);
+                goto disable_clk_topcrm;
+        }
+
+        ret = clk_prepare_enable(priv->clk_apb);
+        if (ret) {
+                dev_err(&pdev->dev, "failed to enable apb clock: %d\n",
+                        ret);
+                goto disable_clk_topcrm;
+        }
+
+        mutex_init(&priv->lock);
+        priv->tzd = thermal_zone_of_sensor_register(&pdev->dev,
+                                        0, priv, &zx2967_of_thermal_ops);
+
+        if (IS_ERR(priv->tzd)) {
+                ret = PTR_ERR(priv->tzd);
+                dev_err(&pdev->dev, "failed to register sensor: %d\n", ret);
+                goto disable_clk_all;
+        }
+
+        if (priv->tzd->tzp->slope == 0) {
+                thermal_zone_of_sensor_unregister(&pdev->dev, priv->tzd);
+                dev_err(&pdev->dev, "coefficients of sensor is invalid\n");
+                ret = -EINVAL;
+                goto disable_clk_all;
+        }
+
+        priv->dev = &pdev->dev;
+        platform_set_drvdata(pdev, priv);
+
+        return 0;
+
+disable_clk_all:
+        clk_disable_unprepare(priv->clk_apb);
+disable_clk_topcrm:
+        clk_disable_unprepare(priv->clk_topcrm);
+        return ret;
+}
+
+static int zx2967_thermal_exit(struct platform_device *pdev)
+{
+        struct zx2967_thermal_priv *priv = platform_get_drvdata(pdev);
+
+        thermal_zone_of_sensor_unregister(&pdev->dev, priv->tzd);
+        clk_disable_unprepare(priv->clk_topcrm);
+        clk_disable_unprepare(priv->clk_apb);
+
+        return 0;
+}
+
+static const struct of_device_id zx2967_thermal_id_table[] = {
+        { .compatible = "zte,zx296718-thermal" },
+        {}
+};
+MODULE_DEVICE_TABLE(of, zx2967_thermal_id_table);
+
+#ifdef CONFIG_PM_SLEEP
+static int zx2967_thermal_suspend(struct device *dev)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct zx2967_thermal_priv *priv = platform_get_drvdata(pdev);
+
+        if (priv && priv->clk_topcrm)
+                clk_disable_unprepare(priv->clk_topcrm);
+
+        if (priv && priv->clk_apb)
+                clk_disable_unprepare(priv->clk_apb);
+
+        return 0;
+}
+
+static int zx2967_thermal_resume(struct device *dev)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct zx2967_thermal_priv *priv = platform_get_drvdata(pdev);
+        int error;
+
+        error = clk_prepare_enable(priv->clk_topcrm);
+        if (error)
+                return error;
+
+        error = clk_prepare_enable(priv->clk_apb);
+        if (error) {
+                clk_disable_unprepare(priv->clk_topcrm);
+                return error;
+        }
+
+        return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(zx2967_thermal_pm_ops,
+                         zx2967_thermal_suspend, zx2967_thermal_resume);
+
+static struct platform_driver zx2967_thermal_driver = {
+        .probe = zx2967_thermal_probe,
+        .remove = zx2967_thermal_exit,
+        .driver = {
+                .name = "zx2967_thermal",
+                .of_match_table = zx2967_thermal_id_table,
+                .pm = &zx2967_thermal_pm_ops,
+        },
+};
+module_platform_driver(zx2967_thermal_driver);
+
+MODULE_AUTHOR("Baoyou Xie <baoyou.xie@linaro.org>");
+MODULE_DESCRIPTION("ZTE zx2967 thermal driver");
+MODULE_LICENSE("GPL v2");